Aqua ammonia is not stable and has to be injected into the ground. It will tend to stay in a band, it will not spread out like anhydrous. If conditions are wet, tight soils, clay, etc. this can be quite a issue. The corn roots will have to grow to the band for N. It is safer then anhydrous ammonia but still has a kick to it if you get a wiff of it. Safer handling is the only benefit I see with aqua ammonia over anhydrous.